The overall goal of this project is to gain an understanding of retinal function. For the next 5 years, we are focusing our efforts on attempting to identify the neurotransmitters used by the retinal neurons and especially on the effects these substances have on retinal cells. Much of the work planned will utilize isolated retinal cells maintained in culture for periods of days to weeks. Five specific projects are proposed: 1) Patch and voltage clamping of isolated horizontal and bipolar cells of the carp and skate retina. This project is studying by patch clamping techniques the response of the horizontal cell membrane to L-glutamate and its analogues. We plan in particular to use patch clamp electrodes to voltage clamp the isolated cells in order to study the ion flows that occur in these cells in response to neurotransmitter substances. 2) An analysis of the ionic mechanisms underlying the responses of isolated and cultured horizontal and bipolar cells of the carp and skate retinas to various neurotransmitter agents, and a quantitative evaluation of the effects of neurotransmitter agonists and antagonists on these neurons. For these experiments, drugs or altered Ringer's solution will be applied to the isolated cells by a microperfusion technique. 3) A physiological and pharmacological study of neurons in culture other than horizontal and bipolar cells, and a study of isolated neurons maintained in culture that are derived from animals other than fish. We are particularly interested in maintaining amacrine cells in culture and studying their physiological and pharmacological properties and also studying isolated retinal neurons from a mammal, perhaps rabbit, in culture. 4) A study of synapse formation between neurons maintained in culture and a physiological and pharmacological analysis of such synapses. Initially we plan to study electrical synapse formation between cultured horizontal cells, but eventually we hope to induce and study chemical synapse formation between a variety of retinal cells. 5) An analysis of the effects of drugs and altered Ringer's solution on neurons in the intact perfused retina. These experiments are intended to complement the isolated cell studies by comparing the effects of drugs and/or altered Ringer's solution on isolated cells with the effects of the same treatments on cells in the intact retina.